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Ambulatory blood pressure monitors ‘inaccurate’

A systematic review has found many ambulatory blood pressure monitors GP practices will have to invest in to meet new NICE guidance ‘may not be sufficiently accurate for clear diagnoses'. 

The study presented at the Society for Academic Primary Care annual conference in Bristol this month showed nearly one monitor in three was inaccurate by more than 5mmHg.


Final NICE guidance out next month will recommend GPs use ambulatory blood pressure monitoring to confirm new diagnoses of hypertension, which experts have predicted will increase the number of patients on hypertension registers.

But Pulse has revealed hospital cardiology departments are ill-equipped to take on referrals and the bulk of ambulatory blood pressure monitoring will have to be done in primary care, with practices expected to invest in new devices costing around £1,500 per monitor.

Primary care researchers reviewed 26 studies using 17 different ambulatory blood pressure monitors. 25 studies of these used a validation protocol, but only six of these correctly adhered to their respective protocol. Two monitors failed validation.

In 13 studies a difference of more than 5mmHg from the reference standard was found for 30% or more of readings. Almost half of all readings were more than 5mmHg from the reference standard of two monitors.

Dr James Hodgkinson, a research fellow in primary care clinical sciences at the University of Birmingham, concluded: ‘Many ambulatory monitors that have apparently passed validation may not be sufficiently accurate for clear diagnostic decision making in clinical practice.'